A shaving device as defined in the opening paragraph is known, for example from U.S. Pat. No. 6,357,118. The shaving device as described in this publication is a dry shaving apparatus comprising a housing, a shaving head frame mounted on the housing, and a shaving head with at least two cooperating cutting elements, at least one of the cooperating cutting elements being a reciprocating cutting element. Furthermore, the shaving device comprises a supporting frame which is coupled to the housing. In particular, the supporting frame has two support arms for mounting the shaving head within the shaving head frame, and also has a function in defining a pivot axis. Between the shaving head frame and the two support arms of the supporting frame, a conical bearing is located, wherein a spring is provided for applying a spring force to the conical bearing. The shaving head is mounted and held for pivotal movement about the pivot axis by the conical bearing acted upon by the spring force of the spring element.
For the purpose of driving the reciprocating cutting element, the shaving device known from U.S. Pat. No. 6,357,118 comprises an electric drive mechanism being provided within the housing, and having a drive element for the transmission of a driving motion to the cutting element. The drive element is configured as a rotary shaft to which an eccentric drive configured as a double eccentric drive is secured in order to transmit the driving motion from the drive element, through an opening in a wall of the supporting frame, to an oscillatory bridge structure provided in the shaving head frame. The oscillatory bridge structure has a slot of a dovetail-type configuration in which a pin of the eccentric drive configured as a double eccentric drive engages. The supporting frame with the support arms provided thereon ensures an oscillatory motion of the shaving head in the direction of movement of the reciprocating cutting element in addition to ensuring, through conically formed joints, a pivotal motion of the shaving head about a pivot axis. With respect to the orientation of this pivot axis, it is noted that provided at the ends of the two support arms of the supporting frame is a respective cone, which is arranged such that the pivot axis extends through the apices of the cones with the shaving head in mounted condition.
A main function of the pivotable arrangement of the shaving head in the housing of the known shaving device as described above is allowing for contour following during use of the shaving device. Only very skilled users are able to moving and positioning a shaving device in such a way that the device is used to its full potential, wherein such users usually need a mirror to check their handling of the device. Therefore, it is desirable to have a shaving device which is adapted to automatically perform contour following by having an adjustable position of the cutting elements with respect to a housing of the device, as a level of performance of the device is related to the way in which cutting elements are placed on skin to be shaved.
The shaving device known from U.S. Pat. No. 6,357,118 is adapted to allow for automatic contour following. However, its construction is rather complex, which is related to the fact that a considerable number of components is involved in allowing for a pivoting movement of the shaving head in the housing of the device during use of the device. Also, it is true that the electric drive mechanism is mounted for oscillation by means of a pivot bearing. In view of the fact that this mechanism is relatively heavy, this does not contribute to convenient handling of the shaving device by a user.
WO 2005/092579 discloses a shaving apparatus having two hair cutting elements, wherein each of the hair cutting elements is provided with a row of substantially V-shaped teeth having cutting edges. A cutting opening is present between each pair of cooperating teeth and has a shearing angle between 0° and 30°. During operation of the shaving apparatus, the cutting openings are not entirely closed, as a result of which skin damage is considerably reduced.
A characteristic feature of the shaving apparatus known from WO 2005/092579 is that the stroke of the movement which is performed by the hair cutting elements with respect to each other during operation may be in a range of 10 μm tot 150 μm. To those familiar with shaving apparatus, it will be apparent that this is a relatively small stroke. In order to avoid a situation in which no stroke remains when the shaving apparatus is used and the cutting elements experience a load, a high stiffness of the cutting elements and a drive train of these elements is needed, for example, a stiffness which is at least 3 N/μm. In other words, in order to avoid deterioration of the shaving performance of the shaving apparatus, it is important that a stiffness of components and connections between components of the shaving apparatus is high, from a motor for providing a driving force to tips of the teeth of the hair cutting elements.